[PATCH 1/2] trace-cruncher: Add generic methods for printing

["Yordan Karadzhov (VMware)" <y.karadz@gmail.com>]

The new methods makes it easy to print:
 - the name and PID of the process that generated the trace record,
 - the unique fields of the record (called also 'info') or
 - all information for the event all together.

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@gmail.com>
---
 examples/kprobe_open.py |   8 +-
 src/ftracepy-utils.c    | 159 ++++++++++++++++++++++++++++++++++++++++
 src/ftracepy-utils.h    |   9 +++
 src/ftracepy.c          |  15 ++++
 4 files changed, 186 insertions(+), 5 deletions(-)

diff --git a/examples/kprobe_open.py b/examples/kprobe_open.py
index f8d4d8b..5b217d3 100755
--- a/examples/kprobe_open.py
+++ b/examples/kprobe_open.py
@@ -26,12 +26,10 @@ open_probe.add_ptr_arg(name='mode',
 
 open_probe.register()
 
+tep = tc.local_tep()
+
 def callback(event, record):
-    if event.id() == open_probe.id():
-        file_name = event.parse_record_field(record=record, field='file')
-        flags = event.parse_record_field(record, 'flags')
-        mode = event.parse_record_field(record, 'mode')
-        print('file: {0}  (flags: {1}; mode: {2})'.format(file_name, hex(flags), hex(mode)))
+    print(tep.info(event, record))
 
 
 if __name__ == "__main__":
diff --git a/src/ftracepy-utils.c b/src/ftracepy-utils.c
index 6739db7..3c000a7 100644
--- a/src/ftracepy-utils.c
+++ b/src/ftracepy-utils.c
@@ -298,6 +298,162 @@ PyObject *PyTep_get_event(PyTep *self, PyObject *args,
 	return PyTepEvent_New(event);
 }
 
+static struct trace_seq seq;
+
+static bool init_print_seq(void)
+{
+	if (!seq.buffer)
+		trace_seq_init(&seq);
+
+	if (!seq.buffer) {
+		PyErr_SetString(TFS_ERROR, "Unable to initialize 'trace_seq'.");
+		return false;
+	}
+
+	trace_seq_reset(&seq);
+
+	return true;
+}
+
+static char *get_comm_from_pid(int pid)
+{
+	char *comm_file, *comm = NULL;
+	char buff[PATH_MAX];
+	int fd, r;
+
+	if (asprintf(&comm_file, "/proc/%i/comm", pid) <= 0) {
+		MEM_ERROR;
+		return NULL;
+	}
+
+	/*
+	 * This file is not guaranteed to exist. Return NULL if the process
+	 * is no longer active.
+	 */
+	fd = open(comm_file, O_RDONLY);
+	free(comm_file);
+	if (fd < 0)
+		return NULL;
+
+	r = read(fd, buff, PATH_MAX);
+	close(fd);
+	if (r <= 0)
+		return NULL;
+
+	comm = strdup(buff);
+	if (!comm)
+		MEM_ERROR;
+
+	return comm;
+}
+
+static void print_comm_pid(struct tep_handle *tep,
+			   struct trace_seq *seq,
+			   struct tep_record *record,
+			   struct tep_event *event)
+{
+	int pid = get_pid(event, record);
+	if (!tep_is_pid_registered(tep, pid)) {
+		char *comm = get_comm_from_pid(pid);
+		if (comm) {
+			tep_register_comm(tep, comm, pid);
+			free(comm);
+		}
+	}
+
+	tep_print_event(tep, seq, record, "%s-%i",
+			TEP_PRINT_COMM,
+			TEP_PRINT_PID);
+}
+
+static void print_name_info(struct tep_handle *tep,
+			    struct trace_seq *seq,
+			    struct tep_record *record,
+			    struct tep_event *event)
+{
+	trace_seq_printf(seq, " %s: ", event->name);
+	tep_print_event(tep, seq, record, "%s", TEP_PRINT_INFO);
+}
+
+static void print_event(struct tep_handle *tep,
+			struct trace_seq *seq,
+			struct tep_record *record,
+			struct tep_event *event)
+{
+	tep_print_event(tep, seq, record, "%6.1000d ", TEP_PRINT_TIME);
+	print_comm_pid(tep, seq, record, event);
+	tep_print_event(tep, seq, record, " cpu=%i ", TEP_PRINT_CPU);
+	print_name_info(tep, seq, record, event);
+}
+
+static bool print_init(PyObject *args, PyObject *kwargs,
+		       struct tep_event **event,
+		       struct tep_record **record)
+{
+	static char *kwlist[] = { "event", "record", NULL};
+	PyTepRecord *py_record;
+	PyTepEvent *py_event;
+
+	if (!init_print_seq())
+		return false;
+
+	if(!PyArg_ParseTupleAndKeywords(args,
+					kwargs,
+					"OO",
+					kwlist,
+					&py_event,
+					&py_record)) {
+		return false;
+	}
+
+	*event = py_event->ptrObj;
+	*record = py_record->ptrObj;
+
+	return true;
+}
+
+PyObject *PyTep_event_record(PyTep *self, PyObject *args,
+					  PyObject *kwargs)
+{
+	struct tep_record *record;
+	struct tep_event *event;
+
+	if (!print_init(args, kwargs, &event, &record))
+		return NULL;
+
+	print_event(self->ptrObj, &seq, record, event);
+
+	return PyUnicode_FromString(seq.buffer);
+}
+
+PyObject *PyTep_info(PyTep *self, PyObject *args,
+				  PyObject *kwargs)
+{
+	struct tep_record *record;
+	struct tep_event *event;
+
+	if (!print_init(args, kwargs, &event, &record))
+		return NULL;
+
+	print_name_info(self->ptrObj, &seq, record, event);
+
+	return PyUnicode_FromString(seq.buffer);
+}
+
+PyObject *PyTep_process(PyTep *self, PyObject *args,
+				     PyObject *kwargs)
+{
+	struct tep_record *record;
+	struct tep_event *event;
+
+	if (!print_init(args, kwargs, &event, &record))
+		return NULL;
+
+	print_comm_pid(self->ptrObj, &seq, record, event);
+
+	return PyUnicode_FromString(seq.buffer);
+}
+
 static bool check_file(struct tracefs_instance *instance, const char *file)
 {
 	if (!tracefs_file_exists(instance, file)) {
@@ -2222,4 +2378,7 @@ void PyFtrace_at_exit(void)
 {
 	destroy_all_kprobes();
 	destroy_all_instances();
+
+	if (seq.buffer)
+		trace_seq_destroy(&seq);
 }
diff --git a/src/ftracepy-utils.h b/src/ftracepy-utils.h
index 5d7c19c..aca1ccc 100644
--- a/src/ftracepy-utils.h
+++ b/src/ftracepy-utils.h
@@ -44,6 +44,15 @@ PyObject *PyTep_init_local(PyTep *self, PyObject *args,
 PyObject *PyTep_get_event(PyTep *self, PyObject *args,
 				       PyObject *kwargs);
 
+PyObject *PyTep_event_record(PyTep *self, PyObject *args,
+					  PyObject *kwargs);
+
+PyObject *PyTep_info(PyTep *self, PyObject *args,
+				  PyObject *kwargs);
+
+PyObject *PyTep_process(PyTep *self, PyObject *args,
+				     PyObject *kwargs);
+
 PyObject *PyFtrace_dir(PyObject *self);
 
 PyObject *PyFtrace_create_instance(PyObject *self, PyObject *args,
diff --git a/src/ftracepy.c b/src/ftracepy.c
index e3fec7b..e948b15 100644
--- a/src/ftracepy.c
+++ b/src/ftracepy.c
@@ -68,6 +68,21 @@ static PyMethodDef PyTep_methods[] = {
 	 METH_VARARGS | METH_KEYWORDS,
 	 "Get a PyTepEvent object."
 	},
+	{"event_record",
+	 (PyCFunction) PyTep_event_record,
+	 METH_VARARGS | METH_KEYWORDS,
+	 "Generic print of a trace event."
+	},
+	{"process",
+	 (PyCFunction) PyTep_process,
+	 METH_VARARGS | METH_KEYWORDS,
+	 "Generic print of the process that generated the trace event."
+	},
+	{"info",
+	 (PyCFunction) PyTep_info,
+	 METH_VARARGS | METH_KEYWORDS,
+	 "Generic print of a trace event info."
+	},
 	{NULL}
 };
 
-- 
2.30.2